SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd48803c1cc9d99be976c7402055c98eb95af7acde21caabd06bc774a522091ed' 
  AND token = 'VkTXPDUnrH2cmli/cc5AuVoZPAuN8eWZF3kEXtwveoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}